Reaction of Acyl Halide with Ammonia or Amine
Among acyl derivatives, amides are next in stability to carboxylic acids, and both are more stable than acid halides. Just as water will easily hydrolyze an acid halide to form a carboxylic acid, ammonia will aminolyze an acid halide to form an amide. These types of reactions are characterized by the pattern of the electropositive acyl carbon accepting a pair of electrons from the nucleophile while shifting a bond pair over to oxygen, forming the tetrahedral intermediate. The amide product is formed after departure of the halide leaving group. The conjugate acid of the amide has formed, which is a stronger acid than hydrogen halide, so proton transfer occurs onto the halide ion. The amide product will therefore be accompanied by hydrogen halide. Thus two equivalents of ammonia are consumed in the reaction, one consumed in neutralizing the acidic hydrogen halide.